If an approaching driver refuses to switch his high beams to low you should .?

Slow down and stop if necesary
Legally, your supposed to look to the right towards the ditch until they go by.

But use common sense if you don't, if your not tailgating some one and there's little traffic just "quickly" switch you lights a "couple" of times to remind them. Some people do forget. If they don't, just suck it up and deal with it. No sense having to "bart" heads out there.
Do nothing but get annoyed if you try to out blind him other people are also getting blinded by you. if he cant see where he is going you are one of the people he is heading for. and even if he misses you and has an accident there might be other people in his car that don't deserve to get hit. the roads are full of idiots and when you take on driving you should understand this.
Look at the road markers on the side of the road. NOT flash your headlight at the other car.